1. Field of the Invention
The present invention relates to a multicast controlling apparatus and method in multi hop networks, and more particularly, to a multicast controlling apparatus and method that is effective, reliable, and capable of supporting multicast in multi hop networks.
2. Description of the Related Art
A multi hop network apparatus may be constituted by a mesh router and a mesh client, namely, a station. Here, the mesh router is connected with another mesh router, a mesh client, or a wired network, and relays a message between the connection.
The mesh router may perform a similar function as a bridge in network equipment. Generally, the network equipment constituted by bridges may use a spanning tree protocol (STP) to prevent a loop. Also, the network equipment constituted by bridges may use an Internet group management protocol (IGMP) snooping to effectively support multicast.
However, when a conventional method is applied to the multi hop network apparatus, various problems may occur.
As an example, according to the conventional method, a group management message may be transmitted based on a tree generated by the STP. That is, the group management message is not transmitted to a port that is blocked by the SPT. Accordingly, the group management message is transmitted based on the tree generated by the STP in a multicast transmission route generate by an IGMP snooping. However, the tree generated by the STP is formed centering around a single route bridge, and the tree is not optimized for a multicast router or a multicast source, thereby not being optimized for multicast transmission route.
Also, when a multicast frame is transmitted in a wireless network, unlike the wired network, a loss may occur. That is, in the conventional method, when the group management message is transmitted based on multicast, a packet loss may occur, and thus, a new station may not receive the multicast or the reception may be delayed. Also, there is a problem that it takes a significant amount of time, when the station leaves.
In addition, the conventional method defines a separate protocol for the wireless network, and thus, there may be problems in that the conventional method is dependent upon a specific unicast routing protocol, the conventional method is not compatible with existing equipment and an application program to embody the specific unicast routing protocol is complex, the group management message is inconsistent, the conventional method is not applicable to a 2-layer based wired network environment, and the like.